Controlling device for refrigerator systems



Feb. 26, 1952 H. c. MILLER CONTROLLING DEVICE FOR REFRIGERATOR SYSTEMSFiled Feb. 16, 1949 INVENTOR.

Ha Ward 6/ 1 2' Z Z67.

7AM p A/ ag/2F I A i My 0 Z ATTORNEY Patented Feb. 26, 1 952 OFFICECONTROLLING DEVICE REFRIGER ATOR SYSTEMS Howard C. Miller, New York, N.Y.

Application February 16, 1949, Serial N 0. 76,840

' 8 Claims. (01. 62--8) This invention is an improvement in controllingdevices; and particularly controlling devices for refrigerating systemsof the compression and evaporation type.

An important object of my invention is to provide a thermostaticcontrolling device that is efficient and certain in operation, and withthe thermostatic element manually charged or self-charging uponinstallation, so that it does not have to be charged separately or inadvance to prepare it for mounting in the system of which it is a part.It therefore contains the same refrigerant as the system, is verysensitive, fully responsive only to changes within the system andnormally unaffected by conditions outside of the same.

A further object is to provide a simpleand practical thermostaticcontrolling device that can beeasily incorporated into the system, isstrong, tight, durable, virtually proof against damage by accidents, andso constructedthat it can be easily and quickly repaired if a leakoccurs, merely by replacement of the principal element therein.

Another object is to provide a refrigerant controlling device capable ofacting at a comparatively smaller difference between the pressure in itsown thermal element and the pressure in the system, thereby increasingthe evaporator coil capacity.

' A still further object is to provide. a thermostatic refrigerantcontrolling device containing a thermal element into which, afterinstallation in a system, a gaseous charge of refrigerant is forcedautomatically at a limited pressure, proper and best suited for thatindividual system; such limited charge having the efiect of preventingan overload on the compressor and motor during the initial period of therunning cycle; and any damage during the idle period, especially wheninstalled under abnormal conditions so that the thermal device isexposed to high temperature outside atmosphere. I

The nature and advantages of the invention are fully described hereinand the novel features are pointed out in the claims. 'But thisdisclosure is by way of example only and I may vary the details of theconstruction illustrated, with.-.

out departing from the general the invention is embodied On thedrawings, Figure 1 shows inoutline tion system containing my invention;

design in which.

Figure 2 shows in section a'modification ofv my controlling device; and

part of a refrigera- Figure 3 a further modification.

An expansion or evaporation coil is indicated at I. It is supplied withrefrigerant through a pipe joined to a connecting element or coupling 2that is screwed into tight union with the ex pansion valve casing 3. Theliquid refrigerating medium flows into the coupling 2 and through thecasing to the coil I, where it starts to expand and evaporate into agas, and the opposite end or outlet of this coil is joined to a coupling4 to which is joined thereturn connection or suction pipe that conductsthe gaseous refrigerant back to the compression pump. In the easing 3 isa valve 5, which cuts off communication when closed between the supplypipe and the coil I. The valve is engaged by a compression spring 6 thattends to hold it against its seat, and the stem 1 of this valve isconnected to a diaphragm 8, or it may just make contacttherewith.

The valve 5 operates in a well-known manner to admit the refrigerant tothe coil I as required. The casing has a hollow boss on its exterior andthe diaphragm is secured against the outer rim of this boss by a, screwcap 9. This cap 9 is coupled to a pipe II] by a soldered or threadedconnection. The pressure space 29 within the boss under the cap 9permits movement of the diaphragm 8, and when the latter is forcedinward by an excess of pressure above it, the valve 5 is opened. Theforce of the spring 6 is regulated by a screw stem 1 l in the casing 3,the stem projecting from the casing and being covered by a screw cap l2.Leakage is prevented by the gland Packing 32, compressed by the threadednut 33.

. The pipe In is united to the coupling t by a soldered connection, or athreaded connection, as desired. The coupling 4 has the form of a T orother convenient shape with a short stem represented by a boss [3enclosing a chamber 39, with an aperture at its inner end or bottom andcommunicating with the bore of the coupling 4. The bottom has an annularshoulder [4 which serves as a seat for a member l5 having a rim I6resting on the shoulder l4 and making sealed or leakproof contacttherewith. The edge of the shoulder may have the form of a rib inrelief, so that the rim I6 can engage it panded end 20 of the pipe Ill.

tobetter advantage. A cap I! is screwed on to the boss I3 and this caphas a neck l8 with a duct l9 extending therethrough. The outer end ofthe neck is conical and over it fits the ex- The connection is completedby means of a cap or coupling nut 2! which binds the end of the pipe onthe neck. A spring 22 in the boss 13 presses against the cap I! at oneend and upon the member l at the other and holds the latter against theseat [4. Opposite the member 15, the bore of the coupling 4 may beprovided with a baflie projection 23.

The casing 3 with the valve 5 and diaphragm 8 therein is a well ,knownunit and, except for the upper thermostatic portion, forms no part ofthis invention; which relates chiefly to the coupling 4 and the thermaldevice or unit which consists of the heat exchanging or transmittingmember [5, the thermal chamber 39, the=connecting pipe Ill, the pressurespace 29, and the-diaphragm 8; or, in place of diaphragm 8, afiexiblemetal bellows that has a similar purpose and function as the diaphragm8. fl l'i'emonstruction and operation details described herein relatemainly to the application of the thermal device to the so-calledthermostatic expansion valve of the diaphragm type, but -iti's equallyapplicable to the thermostatic expansion valve 'of the bellows type,"and also to "o'thehv'arieties of controls,switches and safety devices.

Inmany ordinary refrigerating systems oft-his kind, the pipeiilleading-fromthe casing 3termihates in a bulb 'which is 'secured tothe *outside of the coil l adjacent the-suction-or=outlet end by abolted metal clamp, said bulb, pipe 10 and the pressure space t9 havingpreviously been evacuated of air, charged with a certain refrigerant ata fixed predetermined --pressu-re,-closed, and sealed by soldering in"the -manufacturing process. With-my inventionall of-these-processes areunnecessary, making for e'conomy "in "production, and there is noexternal bulb which often causes less efficientand=responsiveoperationbecause the bulb is subject to conditions outsidethe system as well-as within it.

The thermal device can never contain -the wrong refrigerant, whichshould always be the same as in the system proper, because itis notpre-charged before installation. 'W-hen'firs't connected, andrefrigerant is introduced into the 4 coil l and coupling 4, theincreased pressure raises the member I5 off the seat [I allowing gas toenter thermal chaniber 3-9 and -'-pass up through pipe I 0. Then, nthe-purge or vent plug 36 is loosened, *the air that was the-thermaldevicepasses out, and when plug afi -is retig-htened, the thermal-element is filled with gas at a pressure s'lightly less than that incoil I, the --difference being equal to the light pressure of spring 22.

In most -'compress-ion systems of this type, the operation of thecompressor unit is controlled by a pressure control switch, said switchstarting the motor when the desiredmax'imum pressure is reached in coil:Lcoupling 4, and -'return line 25. When the-compressor starts-areduction in pressure occurs in return-line 2'5,*coupl-ing 4, coil 1,and easing 3, and onthe inner su-rface of diaphragm 8, but the pressureinthe'thermal device and on the outer surface -of-diaphragm 8 does notimmediately drop, but remains --at'the same level, which is nearlyequaltothem-aximum, or starting pressure of the system. Thus an excessof pressure is produced on the outer surface of the diaphragm 8, andwhen this excess pressure overcomes the opposing pressure ofthe spring6, the valve 5 is forced away from its seat,allowing liquid refrigerantto flow into coil I. The charge contained in'the thermal device issuperheated gas with the pressure automatically thermal chamber b9.

limited to the particular maximum operating pressure in that individualsystem, or only slightly less. Thus, since the suction pressure dropsrapidly after the compressor starts until valve 5 opens, and since ahigh operating suction pressure usually causes an overloaded conditionin the compressor and motor, the automatic limited charge acts to reducethe time period of such over oaded condition to "negligible proportions.

If, due ito unusual conditions, the casing 3, pipe [0 and coupling 4,are placed in the open ,air outside the refrigerated space, as has been"done in prior systems a high pressure charge in itheithermal -devicemayforce valve 5 open during the idle period, causing a flooded conditionin the lowpressure portion of the system, with probable damagingresults. The low automatic limited charge will not i'force valve 5 toopen no matter how .high the ambient temperature, because superheatedgas expands but very little with considerable increase in temperature.

it, as with certain high temperature evaporators, a warmer-Hence chargehigher than'the maximum operating pressure is required, this highercharge is =easiiy effected manually, by turning the electrical "switchoff and raising the as pressure :in-cofl 'and"'c',oupling 4 to a pointslightly above the pressure required in the then mal device, during"which process gas forced into the same at the proper pressure, and "the'system is ready for'operation.

With the compressor inopera'tion and valve "'5 in open position,refrigerating performance is somewhat improved over that "of the"conventional expansion valve with externally zclarnped bulb.'Evaporating liquid refrigerant flows through coil l, and gas slightlysuperheatedab'ove the temperature ofth'e evaporating liquid passesthrough coupling '6, in intimate contact with member 15 and the gas inthermal chamber :39, the temperatureof the latter "being substantiallythe same as that of the gas "flowing through coupling l. Thermal chamber39 hassufiicient space to contain, when condensed, all 'of the'gas inthe thermal device, including pipefllr'andpressure space 2 9, andaccording' ly'the pressure in space 29 and onth-eouter surf-ace ofdiaphragm 8 is that which corresponds to *the temperature of the mowchilled and semi-saturated "gas in The temperature {of "the latter ishigher than that of the liquid in'co'il "1,

there exists -'an excess of pressure on the i'outer surface of diaphragm-B --over that -on "the inner surf ace of same, suc'lrexcess-pressurecorresponding elire'ctly to the superheat of the gas in 'coupling l therefrigerant allbeing the "samewith identical pressure-temperaturerelationship. To obtain *maximum capacity and efiiciency "in any coil,the super-heat at its outlet should be "as low as possible providingvalve 5-closes-Whenever, due to liquid surging through intothe"sucticniineafi, such 'superheat approaches, or reaches, zero. Whereasthe conventional expansion valve with externally clamped bulb, due tothe effect of higher ambient temperature, andslowerxand less accurate-response to temperature changes the adjacent suction line, requiresarsuperheat justment averaging about 1'0" theen'closed, intimatelycontacting and sensitive "thermal chamber "39 permits a-superheatadjustment of about 5 or 6 'R with attendant increase-in coil capacityand'efiiciency.

collar 30 resting on theinner end of this nut.

The spring 22 holds the rim 30 against the nut 28. and the member l5projects through the nut into the bore of the coupling so as to be incontact with the refrigerant passing therethrough. The foregoing is acompact, replaceable fitting which screws into the boss l3 on thecoupling 4' by the external threads on fitting 26. The operation of thisdevice is the same as above described.

In Figure 3, the diaphragm 8' in the boss 9 has a central aperture 8a,and the stem I of the valve 5 has a tapered upper end la that can fillthis aperture and obstruct it fully. With this construction the thermalelement is charged through the aperture 80. instead of through cou pling4 or 4'; the springs 22 or 22' are omitted, and the member I5 is firmlyattached to, or made a part of, the wall of coupling 4, or if thefitting of Figure 3 is used, the valve I5 is omitted and the nut 28 hasno hole therein. Charging of the thermal device takes place the same asheretofore described, gas pressure in coil l exerting pressure on theinner surface of diaphragm 8 which is forced outward, away from thepointed end Ia of the valve stem 1'. The aperture 80. is then open andclear for the passage of gas into pipe l and thermal chamber 39 .or 39.Purging is accomplished by loosening of nut 2| or a vent plug openinginto thermal chamber 39 or 39'.

The utility of the device will now be apparent. The construction of thecoupling permits any desired or limited charge into the pipe H] andoperation and control solely by inside conditions is afforded. The screw36 in the cap can be employed for venting or purging. The fitting member26 has a flange or collar 31 which engages tightly the rim of the bossI3.

The superheat in coupling l is controlled by the pressure of the spring6 on the valve 5, said superheat and spring pressure being increased ordecreased by turning adjusting stem ll inward or outward, respectively.

The device requires no external bulb or clamp and need not beprecharged. When it is connected in place the device is self-chargingand all that is necessary when all the connections have been made andthe system itself is charged with refrigerant is to remove the screw 36so that the line Hi can be vented. The refrigerant in the coil I when itfills the coupling 4 in line 25 lifts the valve l5 and fills the line Inwith the same refrigerant that is used in the operation of the system.The charge is limited to the pressure in the coupling 4. The device issuitable for all refrigerants and is completely self-enclosed andself-contained making a separate thermal unit. It can be interchanged orrenewed at will and is well adapted for replacing an old feeler bulbthat has to be clamped to the return pipe 25.

Having described my invention, what I believe to be new is:

1. A refrigerating system having an evaporator coil, a casing containingan expansion valve at the inlet end of the coil, connection forsupplying refrigerant to the coil through the casing and a connectionfor conducting it from the coil at the outlet end, a coupling at theoutlet end of the coil, a heat transferring member in said coupling,means in. said casing for controlling said valve, and an open conduitconnecting said coupling and said means, said couplinghaving.-a..fitting attached thereto, the fittingbeing hollow, and closedby a hollow nut at its inner end, the. member projecting through the nutinto the. coupling, and having afiange at its end engaging said nut,said fitting having aspringthereinpressing said member, and a neck onits outer end secured to the conduit.

2. A refrigerating systemhaving an evaporator coil, a casing containingan expansion valve having a stem at the inlet end of the-coil,connection for supplying refrigerant to-the coil through the casing'andconducting it from the coil at the outlet 'end,l and aconnection for athermal device having an'open pipe united at one end'to the casing andhaving its opposite end disposed "adjacent the outlet of the coil, andmeans for controlling the valve in the casing, said device having amovable heat-transferring part and a portcontrolled thereby to put saidpipe into communication with said last-named connection to'admitrefrigerant in said lastnamed connection to said pipe.

3'. A refrigerating system having an evaporator coil, a casingcontaining an expansion valve having a stem at the inlet end of thecoil, connection for supplying refrigerant to the coil. through thecasin and conducting it from the coil at the outlet end, and aconnection for a thermal device having an open pipe united at one end tothe casing and having its opposite end disposed adjacent of the coil,and means for controlling the valve in the casing, said device having amovable heat-transferring part and a port controlled thereby to put saidpipe into communication with said last-named connection to admitrefrigerant in said last-named connection to said pipe. said part andsaid port being adjacent the outlet of the coil.

4. A refrigerating system having an evaporator coil, a casing containingan expansion valve having a stem at the inlet end of the coil,connection for supplying refrigerant to the coil through the casing andconducting it from the coil at the outlet end, and a connection for athermal device having an open pipe united at one end to the casing andhaving its opposite end disposed adjacent the outlet of the coil, andmeans for controlling the valve in the casing, said device having aheat-transferring part and a port controlled thereby to put said pipeinto communication with said last-named connection to admit refrigerantin said last-named connection to said pipe, said means being in thecasing and having a port therein.

5. A refrigerating system having an evaporator coil, a casing containingan expansion valve at the inlet end of the coil, connection forsupplying refrigerant to the coil through the casing and a connectionfor conducting it from the coil at the outlet end, a heat-transferringmember adjacent said last-named connection at the outlet end of thecoil, means in said casing for controlling said valve, and an openconduit between said means and said member, the connection containingsaid member having an aperture in which said member is movably mountedand a cap over said member and united to the conduit so that said membermay respond to pressure in said last-named connection to admitrefrigerant vapor from said system into said thermal device.

